The Demons Genes
by Miserableandmagicalfairytails
Summary: Warning YOAI! Rin struggles with his demon side to himself. What can Yukio do to help him? In the way does the real truth between the brothers come out? And will Something Different end up happening with Rin and someone else?
1. Chapter 1

A/N

This is my first Ao No Exorcist Fan fiction and my first Yoai Fan fiction as well, go easy on my please. *.* I know some people are going to disagree with me with Yukio being the uke, but I really believe Rin would be the seme. So enjoy guys and tell me what you think about it. If you don't like Yoai don't read.

Yukio's POV:

Rin has been acting strangely lately and I'm starting to worry about him. He hasn't been around any of his friends and barely comes to school. Even if he does come to school he leaves early or at the bell, above all he's avoiding us.

As the rest of the cram school students were finishing up their quiz's I glance over to where Rin sits. It doesn't seem right without him around. Not only at school but he doesn't talk to me at the dorm ether. I promised I would take care of him, and he doesn't seem to want my help. I was snapped out of daze by Bon calling my name.

"Hello, Hello."

"Ah sorry Bon, what's up?"

"We've all finished our papers."

"Okay put them on my desk and you may leave. See you guys tomorrow."

One by one they stacked their papers on my desk and exited the room, as soon as they left I dropped on to the chair and sighed. What was I going to do about Niichan?

Rin's POV

I haven't been myself lately, I think it has to do with the demonic side of me, lots of strange things are happening to me. I got angrier faster and when I am I want to kill everybody, my personalty is slowly changing. I'm becoming more and more harsh as I speak and I'm becoming more distant.

I've found out I like the taste of blood, and it disgusts me. But the thing that has changed the most is that, well, um, I lust for others, but the main point of it is my brother. I can't stay around him for long without wanting to pin him down and do things that would somehow satisfy my need.

I jumped down from the roof and Kuro came to my legs and rubbed against them. I started to walk back to the dorms with Kuro following behind. I jumped through the window and plopped right into bed. I didn't want Yukio to be asking me all these questions, I don't know how long I could how myself back when I'm around him.

Just what I didn't want to happen seemed to start to play out right in front of me, Yukio walked into my room and stood by the door.

"Rin you need to tell me, what is wrong with you?"

"Nothing"

"It's not nothing because you're missing school, barely eating and not talking to anyone. What has gotten into you?"

"Leave"

"Rin tell me."

"Leave now!"

I snapped I couldn't control my temper any longer, as I spoke it came out more as a growl then I statement. I saw Yukio step back as I spoke and stood up. I've never seen him so shocked before.

"R-rin, what has gotten into you?"

"Damn it! Nothing!"

I couldn't hold myself back any more I walked to Yukio and pushed him onto the ground. I had no control over my actions now, I couldn't lie I did want to do this. What the hell is wrong with me!? He's my brother! Why would I want to do this to him? I had to do this now, it was my nature. I try my best to act human, but I can't! The demons genes are stronger in me now.

"R-rin!"

I climbed on top of him and looked down at his frightened expression. I felt like a monster, ether way I am. That became clear to me lately; my human genes are losing out to the demons.

Yukios POV:

What was he doing? I haven't seen him like this before; his expression is of one of a predator that's ready to kill its prey. He moved into me and I couldn't lie he has gotten bigger lately. He was now well over my height and he has gained muscle. Even before I can't lie I couldn't match him in strength .

He shifted his weight and ripped my shirt open exposing my chest. I was in complete shock and my eyes went wide. I blushed from the embarrassment. He moved closer and his mouth crashed into mine, it was a hungry and forceful kiss.

I thought my face was going to burst into flames by the heat that rose to my cheeks. After my shock I started to kiss him back, as soon as I reacted he bite at my bottom lip for access. And I gave it to him.

His tongue slid into my mouth and explored every crevice. I heard a low growl coming from his throat. It didn't sound human, and somehow it turned me on, I could feel myself becoming hard. I felt that Rin was also hard. He continued to assault my lips and I pulled away yelping.

"Ouch!"

Rins POV:

Did he know how much it taking me to hold back right now while he makes that face!? Damn Yukio don't look like that. He pulled away I saw that he had cut his lip on my fangs. I grinned down at him and licked the blood away hungrily. I soon began sucking on his lip, its disgusting but I love this taste.

"R-Rin that hurts."

I smiled a toothy grin and licked the last of his blood off my lip, I couldn't stop anymore. I ripped of his shirt and began to lick and kiss spots up and down his chest.

He began to moan and that turned me on even more. I moved up to his neck and begin sucking on it. Still tasting his blood on my tongue I wanted more. I sank my fangs into his neck and heard him cry out in pain, as I heard his screams my erection grew harder.

Yukio's POV:

My eyes widened as Rin sunk his Fangs into my neck, I screamed out in pain and I felt him become even harder. What is with him?! He was devouring my blood, after a little bit he pulled away and looked down at me and licked the bite marks.

I shivered in the soothing pleasure that it caused me. Rin continued to kiss and lick my chest, then he stopped at my nipples. He licked and nibbled on one while he played with the other. I couldn't take it anymore.

"P-please, stop teasing me."

"If you say so Yukio."

Rin's POV:

Hearing his pleas I lost with was left of my restraint. I slid my hand into his pants and boxers and stroked his hard length. I noticed his heavy breathing and face. I began to strip myself of my clothing except of my boxers and my tail wrapped around his leg.

"It's your turn Yukio."

"T-to do what?"

I gave him a look and he knew what I talking about, after blushing Yukio began t move closer to me and pull my boxers down, he gasped as soon as he had the boxers off. '

"Rin when did you become so big!?"

I laughed, I have become bigger. It happened about a month after I awakened my demonic powers. I firmly grabbed his hair and pulled his mouth towards my length.

"I-I've never done this before so I'll probably be bad at it."

"I don't care, as long as it's you."

Yukio's POV:

Moving down to Rin's erection I licked the top and he growled in what seemed to be pleaser. I moved my tongue along and he grabbed my hair.

"More Yukio."

"O-okay."

I pushed as much as Rin's dick into my mouth and moved back forward and he moaned and growled at almost the same time. He flipped me over and laid onto of me and our both growing erections rubbed together.

I was close to my climax but Rin didn't seem to be there yet. He pumped my dick with one hand while our tongues intertwined. I pulled away gasping for air. Rin didn't even seem to be breathing heavily yet. He continued pumping my length.

"Ah! Rin! I'm going to."

Before I could get any more words out I released. I released onto my stomach and Rin grinned. Rin flipped me onto my stomach and pressed his length to my back.

"lick."

He moved his fingers near my lips and I did as he told me. I coated his fingers in my saliva. He adjusted his weight and hugged me, my body was now shaking, I didn't know what to expect. Rin whispered into my ear.

"Its okay, I'll try to be gentle."

"Thank y-you."

He put one finger into me and I shook.

"It feels weird."

'It'll get better."

He slid another finger into me and another as he prepared me for his length. He shifted and put something onto his part, and moved over and pressed to me. He nibbled on my ear to distract me, I appreciated it but I don't think anything could take away my fear.

"I'm going to put it in now."

"O-okay"

He slowly slid into me and he moaned.

"I-it hurts! Rin it hurts."

Kissing my neck and cheek as I got used to the feeling, he then growled.

Rin's POv:

I know Yukio wasn't ready but I couldn't hold back. I began to thrust slowly and I moaned with each thrust. Slowly I began to thrust harder. I was snapped out of myself when I heard Yukio.

"R-rin, I'm not ready it still hurts."

I slowed myself down and his body relaxed a bit, I moved slowly and he calmed and after I while he was ready and I thrusted slowing. I growled in pleasure and he started to moan.

"H-harder."

"I'll hurt you.'

"i-I'll be fine."

I began thrusting faster and harder and both I and Yukio moaned, I soon came close to my climax.

Yukio's POV:

I didn't know how much longer I can go, how is Rin still going? I soon felt him release in side of me. We both sighed out of comfort and I collapsed onto the bed, Rin catching me and lying next to me. He kissed my forehead and smiled.

"You okay Yukio?"

"Ya I'm fine."

"I-I'm sorry."

"Why are you sorry!?"

"B-because I forced you."

"I don't care, truthfully Rin I care for more than just a brother. Now tell me what's gotten into you lately."

A/N

Tell me what you guys thought, it probably sucked but i'm going to try it out anyway.


	2. Chapter 2

A/N

Okay guys, sorry for not updating, life doesn't seem to like me right now. Anywho, after this Chapter many people are probably going to hate me. BUT sorry, I need to continue with my plans for this FanFiction. This Chapter is going to be really short, promise I will update ether later tonight or tomorrow. So without Farther Ado, Chapter 2 for you guys.

Chapter 2:

~Rins POV

"I can't go back to school!"

"Rin, you can't just stay here all the time!"

"I'll hurt someone! I could hurt you."

"Hurt me! I don't care, do you know why?!"

"What the hell would make you okay with being hurt?

As he heard me continue, he looked shocked and that stern expression slide off his face. He stared down at the floor and I heard him mumble something. Even with my advanced hearing I couldn't quite make it out. He soon looked up and stared me in the eye.

"I WOULD BE OKAY WITH YOU HURTING ME BECAUSE ITS YOU! R-rin, I love you. I didn't know it was love until we found out that you were a demon and everyone was leaving you no matter what I couldn't leave you. You are so important to me and I don't care what has to happen as long as I'm next to you. I I LOVE YOU IDIOT!"

I was shocked I didn't know what to say, why would anyone love me? I'm just a worthless demon. Everyone's life would be easier without me.

"Y-you love me?"

I looked forward and saw Bon smiling with trying to look inviting instead of scary. What was going on?!

A/N

AHHH DON'T HATE ME! Trust me I have lots of surprises in store for this FanFiction. Another update will be up soon no need to worry.


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